Measuring instruments arc well known and commonly used to measure and monitor various conditions such as temperature, pressure, humidity, and the like of a particular source or product. Typically, a measuring instrument includes a sensing clement, a movement, and an indicator. In order to operate effectively and provide the desired result, the movement usually must perform the following two functions: (1) amplification of the motion of the sensing clement, and (2) conversion of the sensing element's motion to angular motion. In addition, the movement assembly often must also be able to convert the motion of the sensing element into angular motion which is in a plane perpendicular to the direction of the sensing element's motion.
Measuring instruments have long been used in a wide variety of applications, due to the need and desire to measure and/or monitor various conditions or levels of certain products, areas, or test equipment. With the ever increasing expansion of both products and processes, the need for such measuring instruments has continued to increase.
Typical prior art measuring instruments are employed to measure or monitor the pressure, temperature, humidity, etc of a particular source, product, or zone. Although all prior art measuring instruments are constructed for measuring one particular condition, measuring instruments generally comprise a similar construction, as discussed above. As a result, one type of measuring instrument, namely a pressure gauge, has been selected for detailed discussion herein as an example of all measuring instruments.
High quality pressure measuring gauges arc principally constructed using sealed elongated tube members as the sensing element. By employing a specially constructed movement assembly, the movement of the sealed elongated tube controls a movable indicator, and the pressure change sensed by the tube is converted to a readable dial which displays the pressure level. Although these gauges provide accurate measuring of desired pressure levels, these prior art gauges are extremely expensive since the formation of sealed tubes capable of attaining this uniform deflection represents a complex and difficult art.
Another type of sensing element employed in pressure gauges is the diaphragm. By exposing one side of a sealed diaphragm to the pressure source, the diaphragm moves along its central axis in response to pressure changes. By measuring the deflection of the diaphragm as its movement varies in response to the pressure being monitored, desired pressure levels and changes are measured and monitored.
Although the use of a diaphragm is substantially less expensive than the sealed tube prior art gauges, diaphragms suffer from three principal shortcomings: (1) movement is small in response to pressure changes; (2) movement is not linearly proportional to pressure changes; and (3) movement is perpendicular to the plane of the gauge dial. As a result, the movement assembly must be constructed to accommodate the shortcomings.
Although consumer demand has long existed for inexpensive pressure measuring/monitoring gauges capable of providing accurate results in a long-term and consistent manner, the industry has only been capable of satisfying this need by providing pressure measuring/monitoring gauges having complex mechanisms which are expensive to produce and assemble. As a result, the resulting products arc incapable of satisfying the ever-increasing need for low cost, reasonably accurate pressure gauges, as well as low cost reasonably accurate measuring instruments in general.
Therefore, it is a principal object of the present invention to provide a measuring instrument which is capable of being produced inexpensively, while also providing accurate results.
Another object of the present invention is to provide a measuring instrument having the characteristic features described above which is capable of being employed in virtually any desired application while providing consistent and repeatable results.
Another object of the present invention is to provide a measuring instrument having the characteristic features described above which employs a minimum of components and, as a result, is capable of being easily and quickly assembled.
Other and more specific objects will in part be obvious and will in part appear hereinafter.